1. Field of the Invention
The invention relates in general to subscription to receive information over a computer network, and more particularly, to podcasting.
2. Description of the Related Art
Podcasting involves distribution of multimedia files over a network, typically the Internet, using a syndication format, for playback on mobile devices or personal computers, for example. Ordinarily, these information content files contain audio or video, but also may contain images, text, PDF, or any file type. By syndication format, it is meant a format used to associate computer readable files. A syndication format is used to associate files that are available for delivery over a network. The syndication format also is used to provide users with information concerning the subject matter or content of files available for download. Based upon information provided in the syndication format, a user may decide to subscribe to delivery of one or more files. Syndication format-aware computer programs then can automatically determine what files to download to subscribing users and to automatically download such files.
A feed is an association among files specified in accordance with a syndication format. Generally, a feed is used to associate files according to criteria specified by a publisher of the content. For example, files associated by a feed may represent episodes in a program similar to episodes of a television or radio program. For instance, a feed may comprise a list of the URLs by which episodes of a show may be accessed over the Internet. A content provider may post a feed on a webserver. This location may be referred to as the feed URI (or, perhaps more often, feed URL). Ordinarily, a feed is updated each time a new file (e.g. episode or media file) is published. Alternatively, a feed may associate files based upon more arbitrary criteria, however, such as files of favorite songs of a particular blogger. The RSS and Atom formats are examples of two popular feed formats. The RSS format is an example of a simple XML-based format that allows users to subscribe to content available for download from networks sites such as Internet websites. An RSS feed comprises an association of files using the RSS format. An Atom feed comprises an association of files using the Atom format.
A user typically uses a type of computer program known as an aggregator, sometimes called a podcatcher or podcast receiver, to subscribe to and manage subscriptions to feeds. An aggregator monitors a set of feeds for a user and downloads file updates at a specified interval, such as every two hours, for example. A downloaded file, such as an episode of a show for example, then can be played, replayed, or archived as with any other computer file.
RSS (Really Simple Syndication) is an example of a simple XML-based feed format that allows users to subscribe to their favorite websites. Using RSS, a webmaster can put content into a well-known format, which can be viewed and organized through RSS-aware software. The web address of a file (e.g. a media file) may be contained in a enclosure tag of an item in an XML file in accordance with RSS 2.0. Two constituents of a typical RSS feed are the channel element and the item element. Both the channel element and the item element may comprise sub-elements. Actually the item element itself is a sub-element of a channel element.
The following is a list of some RSS channel elements, each with a brief description and example.
ElementDescriptionExampletitleThe channel nameentertainment.comlinkURL to the HTMLhttp://www.entertainment.com/website correspondingto the channel.descriptionPhrase or sentenceThe report from entertainment, andescribing the channel.entertainment company Web site.
A channel may contain a number of <item>s. An item also may be complete in itself. Elements of an item are optional. The following lists some RSS item elements, each with a brief description and example.
ElementDescriptionExampletitleThe title of theExcellent New Songitem.linkThe URL of thehttp://publication.com/2006/10/18EAF.htmlitem.descriptionBrief descriptionThe Excellent New Song was released to critical acclaim.of the item.enclosureDescription ofHas three required attributes. url indicating where thean object attachedenclosure is located, length indicating size in bytes, and typeto the item.indicates file type is, e.g. standard MIME type.<enclosureurl=“http://www.songname.com/mp3s/firstsong.mp3”length=“13217840” type=“audio/mpeg” />guidGlobally unique<guid>http://arbitrary.server.com/weblogItem5050</guid>identifier, a stringthat uniquelyidentifies theitem. Whenpresent, anaggregator maychoose to use thisstring todetermine if anitem is new.sourceRSS channel<sourcewhere the itemurl=“http://www.musicreview.org/links2.xml”>moviereview'scame from. (Thelocation</source>purpose of thiselement is topropagate creditfor links)
Thus, podcasting provides a new paradigm for delivery of information over networks. The popularity of podcasting has created a need to develop new approaches to targeting content to users based upon the content to which have subscribed. In particular, for example, there has been increased interest in developing improved techniques to target advertisements to users who subscribe to content. The present invention meets this need.